Disadvantages of early literacy

My parents were visiting recently, and my mother brought an apple pie. After we finished lunch I wanted to get Isaac settled down for his nap, and I wanted to warn my parents to not start eating the pie in front of him. But I knew the very mention of pie would be disruptive, so I used an age-old parental technique: spelling.

I asked my parents, "Would you please wait until later for the p-i-e?"

Isaac looked at me intently, and asked, "What does p-i-e spell?"

Busted!

And of course I told him the truth. What kind of parent lies to their child about spelling? That seems counter-productive in the long run.